Date of Award

May 2015

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Biological Sciences

First Advisor

John Janssen

Committee Members

John Berges, Harvey Bootsma, Timothy Ehlinger, David Jude

Keywords

Competition, Lake Michigan, Round Goby, Yellow Perch

Abstract

A critical step in the recruitment of age-0 yellow perch (Perca flavescens) to the

adult population occurs during their transition to the demersal stage. If larval age-0

yellow perch survive recruitment bottlenecks imposed by alewife (Alosa

pseudoharengus) and dreissenid mussels, they transition to demersal feeding in late

August and early September. In Lake Michigan, demersal age-0 yellow perch seek

rock substrate where they begin feeding on benthic invertebrates in late summer.

That research preceded the invasion of the round goby (Neogobius melanostomus), a

species that can have negative impacts on benthic forage. The current study used

the spread of round gobies as a natural experiment to assess the competitive

interactions between age-0 yellow perch and round gobies. Habitat selection and

diet of age-0 yellow perch in relation to round goby abundance were analyzed using

fish captured in 6.25- and 8-mm bar micro-mesh gill nets in 2006 and 2007 at six

study locations from Sheboygan to Wind Point, Wisconsin. Age-0 yellow perch in

this study significantly shifted habitat (from rock to sand) and diet preferences

(from benthic invertebrates to zooplankton) with increasing round goby abundance.

Round gobies also significantly altered the benthic community composition. I propose demersal age-0 yellow perch in Lake Michigan face a novel recruitment bottleneck caused by a combination of exploitative competition for benthic prey and interference competition with round gobies.

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